1. Field of the Invention
The present invention relates to a supersonic jet crusher of a collisional type using a high pressure gas constituting a jet stream. More particularly, the present invention relates to a supersonic jet crusher of a collisional type for crushing a crushing material consisting of coarse particles into minute particles.
2. Description of the Related Art
For example, in a general electrophotographic copying machine of a dry type, resin, etc. are changed to fine powder and toner composed of the fine powder is used as developing powder.
Such toner is called dry type toner for an electrostatic charge image. When this toner is manufactured, resin, a dye, a pigment, etc. are melted and kneaded in a thermal roller mill. After the kneaded material is cooled, the kneaded material is coarsely crushed by using a jaw crusher, etc. This crushing material is finely crushed by a supersonic jet crusher.
At the present time, there is a requirement for manufacturing toner with reduced cost by crushing the crushing material with high efficiency. However, when such toner is manufactured by the jet crusher, crushing ability is determined by a primary collision between the crushing material and a collisional plate and a secondary collision between the once-crushed material and a wall of a crushing chamber.
In a large-sized jet crusher having a flow rate of a jet stream equal to or greater than 5 m.sup.3 /min, the shape of the secondary collisional plate is limited so as not to effect the maintenance of the crusher.
When a collisional member having a crushing face is used, the crushing face is perpendicular to an injecting direction of the jet stream in which maximum impact force is obtained on the crushing face by a crushing action of the coarse material colliding with the collisional member. However, when toner is actually manufactured, the crushing face is partially worn by the frictional crushing action between the crushing face and a raw material of toner as the crushing material when the jet crusher is continuously operated for a long period. Accordingly, it is impossible to maintain an inclination of the crushing face in which the crushing face is inclined 90.degree. with respect to the injecting direction of the jet stream. Therefore, processing ability of the crusher is reduced.
Accordingly, it is desirable to develop a jet crusher of this kind for continuously maintaining the maximum impact force on the crushing face for a long period with respect to particles having a diameter which are required to be crushed.